Touch sensor and associated control method for decreased capacitive loads

ABSTRACT

A device includes a controller coupled to a touch sensor. The touch sensor includes a first array of capacitive nodes substantially aligned with a second array of capacitive nodes in a mechanical stack. The controller is configured, when in a self-capacitive mode of operation, to send a first drive signal to a plurality of the electrodes of the first array, send a shield signal to at least a portion of the electrodes of the second array at the same time as the first drive signal is sent to the plurality of electrodes of the first array, and sense touch inputs based on signals received from the plurality of electrodes of the first array while the first drive signal is being sent to the plurality of electrodes of the first array and the shield signal is being sent to the at least a portion of the electrodes of the second array.

RELATED APPLICATION

This application is a continuation under 35 U.S.C. § 120 of U.S.application Ser. No. 16/025,354, filed Jul. 2, 2018 and entitled TouchSensor and Associated Control Method for Decreased Capacitive Loads,which is a continuation of application Ser. No. 14/990,974, filed Jan.8, 2016 and entitled Touch Sensor and Associated Control Method forDecreased Capacitive Loads, which is now U.S. Pat. No. 10,013,101 IssuedJul. 3, 2018, which are all incorporated herein by reference.

TECHNICAL FIELD

This disclosure generally relates to touch sensors.

BACKGROUND

A touch sensor may detect the presence and position of a touch or theproximity of an object (such as a user's finger or a stylus) within atouch-sensitive area of touch sensor overlaid on a display screen, forexample. In a touch-sensitive-display application, touch sensor mayenable a user to interact directly with what is displayed on the screen,rather than indirectly with a mouse or touch pad. A touch sensor may beattached to or provided as part of a desktop computer, laptop computer,tablet computer, personal digital assistant (PDA), smartphone, satellitenavigation device, portable media player, portable game console, kioskcomputer, point-of-sale device, or other suitable device. A controlpanel on a household or other appliance may include a touch sensor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1D illustrate an example touch sensor system according tocertain embodiments of the present disclosure.

FIG. 2 illustrates an example two-layer capacitive touch sensor systemaccording to certain embodiments of the present disclosure.

FIGS. 3A-3B illustrate an example capacitive node of a two-layer touchsensor according to certain embodiments of the present disclosure.

FIGS. 4A-4D illustrate blow-up and cross-sectional views of thecrossover region of the capacitive node of FIGS. 3A-3B in accordancewith certain embodiments of the present disclosure.

FIG. 5 illustrates an example method of controlling a two-layer touchsensor in accordance with embodiments of the present disclosure.

DESCRIPTION OF EXAMPLE EMBODIMENTS

The integration of displays and touch sensors (i.e., where the touchsensor and display are in the same mechanical stack and/or electricallycoupled to one another; that is, they may share electrical connections,components, or voltage supplies) can cause significantly increased loadseen by a controller of the touch sensor, especially in self-capacitivemodes of operation. For instance, current touch sensor designs withintegrated displays may have loads between approximately 250 and 1000 pFper sense line or electrode during mutual-capacitive modes of operationwhere only a few (e.g., 1 or 2) lines are driven together at the sametime. During self capacitive modes of operation, all sensor lines aredriven together resulting in much higher capacitive loads. Theseincreased loads seen by the touch sensor controller can impact a numberof aspects related to the performance of the touch sensor or display.For example, display operation, ability to drive the touch sensorelectrodes, touch sensing response time (i.e., the frequency of touchsense determination), controller power consumption, and overall noisehandling may all be affected by touch sensors with high loads.

Accordingly, the present disclosure describes a touch sensor andassociated control method for decreased capacitive loads. For instance,electrodes of a touch sensor according to embodiments of the presentdisclosure may have a load of under 100 pF during self-capacitive modesof operation. In particular, the present disclosure describes atwo-layer touch sensor architecture and an associated touch sensingcontrol method that results in decreased loads seen by a controller,especially during self-capacitive modes of operation using driven shieldsignals on one or more electrodes of the touch sensor.

In one embodiment, for example, a device includes controller coupled toa touch sensor. The touch sensor includes a first array of capacitivenodes disposed above a second array of capacitive nodes in a mechanicalstack forming a plurality of crossover regions. When in themutual-capacitive mode of operation, the controller is configured tosend a first drive signal to one or more first electrodes of the firstarray (e.g., the x-axis electrodes), send the first drive signal to oneor more first electrodes of the second array (e.g., the x-axiselectrodes), and sense touch inputs based on signals received fromy-axis electrodes of the first array. When in the self-capacitive modeof operation, the controller is configured to send a second drive signalto a first plurality of the electrodes of the first array, send a shieldsignal to each of the electrodes of the second array, and sense touchinputs based on signals received from the first plurality of electrodesof the first array.

To facilitate a better understanding of the present disclosure, thefollowing examples of certain embodiments are given. In no way shouldthe following examples be read to limit, or define, the scope of thedisclosure. Embodiments of the present disclosure and its advantages maybe best understood by referring to FIGS. 1-5, where like numbers areused to indicate like and corresponding parts

FIGS. 1A-1D illustrate an example touch sensor system 100 according tocertain embodiments of the present disclosure. Referring to FIG. 1A,touch sensor system 100 comprises a touch sensor 101 and touch sensorcontroller 102 that are operable to detect the presence and position ofa touch or the proximity of an object within a touch-sensitive area oftouch sensor 101. Touch sensor 101 may include a two-layer touch sensorarchitecture in accordance with particular embodiments of the presentdisclosure. For instance, touch sensor 101 may include a top layer and abottom layer, wherein each of the top layer and the bottom layercomprises an array of capacitive nodes formed by electrodes. The arrayof the top layer may be disposed above the array of the bottom layer,such that the capacitive nodes of each layer substantially align to formcrossover regions as discussed below. Touch sensor 101 includes one ormore touch-sensitive areas.

The electrodes of touch sensor 101 include a conductive material forminga shape, such as a disc, square, rectangle, thin line, diamond, othershape, or a combination of these shapes. One or more cuts in one or morelayers of conductive material may (at least in part) create the shape ofan electrode, and the area of the shape may (at least in part) bebounded by those cuts. In certain embodiments, the conductive materialof an electrode occupies approximately 100% of the area of its shape.For example, an electrode may be made of indium tin oxide (ITO) and theITO of the electrode may occupy approximately 100% of the area of itsshape (sometimes referred to as 100% fill). In certain embodiments, theconductive material of an electrode occupies less than 100% of the areaof its shape. For example, an electrode may be made of fine lines ofmetal or other conductive material (FLM), such as for example copper,silver, carbon, or a copper-, silver-, or carbon-based material, and thefine lines of conductive material may occupy only a few percent (e.g.,approximately 5%) of the area of its shape in a hatched, mesh, or otherpattern. Although this disclosure describes or illustrates particularelectrodes made of particular conductive material forming particularshapes with particular fill percentages having particular patterns, thisdisclosure contemplates electrodes made of any appropriate conductivematerial forming any appropriate shapes with any appropriate fillpercentages having any suitable patterns.

FIGS. 1B-1C illustrate example configurations 150 of electrodes in atouch sensor array in accordance with certain embodiments of the presentdisclosure. In particular, configuration 150 a of FIG. 1A compriseselectrodes in a grid pattern, while configuration 150 b of FIG. 1Bcomprises electrodes in a diamond pattern. Each of configurations 150comprises a first set of electrodes 151 and a second set of electrodes152, wherein the first set of electrodes 151 and the second set ofelectrodes 152 overlap to form a plurality of capacitive nodes 153.Although described in particular patterns, the electrodes of touchsensors according to the present disclosure may be in any appropriatepattern. In certain embodiments, for example, first set of electrodes151 may not be horizontal as illustrated and the second set ofelectrodes 152 may not be vertical as illustrated. Rather, the first setof electrodes 151 may be any appropriate angle to horizontal and thesecond set of electrodes 152 may be any appropriate angle to vertical.This disclosure is not limited to the configurations 150 of electrodes151 and electrodes 152 illustrated in FIGS. 1B-1C. Instead, thisdisclosure anticipates any appropriate pattern, configuration, design,or arrangement of electrodes and is not limited to the example patternsdiscussed above.

FIG. 1D illustrates an example mechanical stack 160 that houses touchsensor 101 in accordance with embodiments of the present disclosure.Mechanical stack 160 includes a layer of optically clear adhesive (OCA)162 beneath a cover panel 161. Cover panel 161 may be clear and made ofa resilient material suitable for repeated touching, such as for exampleglass, polycarbonate, polyethylene terephthalate (PET), or polymethylmethacrylate (PMMA). The layer of OCA 162 may be disposed between coverpanel 161 and polarizer 163, which may be operable to polarize light asit passes therethrough.

Mechanical stack 160 also includes touch sensor 101. According toparticular embodiments of the present disclosure, touch sensor 101comprises two layers: top layer 164 and bottom layer 166. Top layer 164and bottom layer 166 each comprise an array of capacitive nodes formedby overlapping electrodes, and each layer may be laid out inconfigurations similar to configurations 150 of FIGS. 1B-1C or in othersuitable configurations. The electrodes and/or capacitive nodes of toplayer 164 may be substantially aligned with the electrodes and/orcapacitive nodes of bottom layer 166 such that crossover regions areformed as described below (e.g., crossover region 305 of FIGS. 3A-3B).That is, electrodes of top layer 164 running in a first direction (e.g.,x-axis electrodes of layer 164) may be aligned with electrodes of bottomlayer 166 running in the same direction (e.g., x-axis electrodes oflayer 166). Similarly, electrodes of top layer 164 running in a seconddirection (e.g., y-axis electrodes of layer 164) may be aligned withelectrodes of bottom layer 166 running in the same direction (e.g.,y-axis electrodes of layer 166). As such, the capacitive nodes formed bythe overlapping electrodes of each layer may also align with oneanother. Electrodes aligned with one another in accordance with thepresent disclosure may be referred to herein as corresponding with oneanother. Top layer 164 and bottom layer 166 are separated in mechanicalstack 160 by insulation layer 165, which may be composed of a dielectricmaterial in some embodiments. As will be described further below,insulation layer 165 may further comprise one or more vias that coupleone or more electrodes of top layer 164 with one or more electrodes ofbottom layer 166.

Mechanical stack 160 further includes an interface layer 167 and adisplay 168. Interface layer 167 includes suitable components forelectronically and/or otherwise communicatively coupling touch sensor101 with display 168. In some embodiments, the display 168 may beintegrated with touch sensor 101 such that one or more electroniccomponents or connections are shared between touch sensor 101 anddisplay 168. Although this disclosure describes a particular mechanicalstack with a particular number of particular layers made of particularmaterials, this disclosure contemplates any suitable mechanical stackcomprising a two-layer touch sensor and having any suitable number ofany suitable layers made of any suitable materials.

In certain embodiments, touch sensor 101 implements a capacitive form oftouch sensing that includes both mutual- and self-capacitive modes ofoperation. In a mutual-capacitive mode of operation, touch sensor 101includes an array of electrodes forming an array of capacitive nodes,which includes drive and sense electrodes. A drive electrode and a senseelectrode may form a capacitive node (e.g., the first set of electrodes151 and the second set of electrodes 152 of FIGS. 1B-1C, respectively,forming capacitive nodes 153). The drive and sense electrodes formingthe capacitive node are positioned near each other, but do not makeelectrical contact with each other. Instead, in response to a signalbeing applied to the drive electrodes for example, the drive and senseelectrodes capacitively couple to each other across a space where theelectrodes overlap each other. A pulsed or alternating voltage appliedto the drive electrode (e.g., by touch sensor controller 102) induces acharge on the sense electrode, and the amount of charge induced issusceptible to external influence (such as a touch or the proximity ofan object). When an object touches or comes within proximity of thecapacitive node, a change in capacitance may occur at the capacitivenode and touch sensor controller 102 measures the change in capacitance.By measuring changes in capacitance throughout the array, touch sensorcontroller 102 determines the position of the touch or proximity withintouch-sensitive areas of touch sensor 101.

In a self-capacitive mode of operation, (in contrast tomutual-capacitive modes of operation), both sets of electrodes (e.g.,both the first set of electrodes 151 and the second set of electrodes152) are driven to create what may be referred to as a“self-capacitance” in the capacitive nodes formed thereby. Theself-capacitance of a capacitive node may refer to the amount of chargeneeded to raise the voltage in the capacitive node by a pre-determinedamount. When an object touches or comes within proximity of thecapacitive node in self-capacitive modes of operation, a change inself-capacitance may occur at the capacitive node and touch sensorcontroller 102 measures the change in self-capacitance (for example, asa change in the amount of charge required to raise the voltage at thecapacitive node by a pre-determined amount). By measuring changes inself-capacitance throughout the array, touch sensor controller 102determines the position of the touch or proximity within touch-sensitiveareas of touch sensor 101.

In certain embodiments, one or more drive electrodes together may form adrive line running horizontally or vertically or in any suitableorientation. Similarly, in certain embodiments, one or more senseelectrodes together may form a sense line running horizontally orvertically or in any suitable orientation. In one particular example,drive lines run substantially perpendicular to the sense lines. However,the drive lines and sense lines of touch sensors according to thepresent disclosure may run in any particular orientation with respect toone another. Reference to a drive line may encompass one or more driveelectrodes making up the drive line, and vice versa. Reference to asense line may encompass one or more sense electrodes making up thesense line, and vice versa.

As described above, a change in capacitance at a capacitive node oftouch sensor 101 may indicate a touch or proximity input at the positionof the capacitive node. Touch sensor controller 102 detects andprocesses the change in capacitance to determine the presence andposition of the touch or proximity input. In certain embodiments, touchsensor controller 102 then communicates information about the touch orproximity input to one or more other components (such as one or morecentral processing units (CPUs)) of a device that includes touch sensor101 and touch sensor controller 102, which may respond to the touch orproximity input by initiating a function of the device (or anapplication running on the device). Although this disclosure describes aparticular touch sensor controller having particular functionality withrespect to a particular device and a particular touch sensor, thisdisclosure contemplates any suitable touch sensor controller having anysuitable functionality with respect to any suitable device and anysuitable touch sensor.

In certain embodiments, touch sensor controller 102 is implemented asone or more integrated circuits (ICs), such as for examplegeneral-purpose microprocessors, microcontrollers, programmable logicdevices or arrays, application-specific ICs (ASICs). Touch sensorcontroller 102 comprises any suitable combination of analog circuitry,digital logic, and digital non-volatile memory. In particularembodiments, touch sensor controller 102 may comprise instructionsstored in a computer-readable medium (e.g., memory), wherein theinstructions are configured, when executed by a processor unit of touchsensor controller 102, to perform one or more functions or steps of amethod. In certain embodiments, touch sensor controller 102 is disposedon a flexible printed circuit (FPC) bonded to the substrate of touchsensor 101, as described below. The FPC may be active or passive. Incertain embodiments, multiple touch sensor controllers 102 are disposedon the FPC.

In an example implementation, touch sensor controller 102 includes aprocessor unit, a drive unit, a sense unit, and a storage unit. In suchan implementation, the drive unit supplies drive signals to the driveelectrodes of touch sensor 101, and the sense unit senses charge at thecapacitive nodes of touch sensor 101 and provides measurement signals tothe processor unit representing capacitances at the capacitive nodes.The processor unit controls the supply of drive signals to the driveelectrodes by the drive unit and process measurement signals from thesense unit to detect and process the presence and position of a touch orproximity input within touch-sensitive areas of touch sensor 101. Theprocessor unit may also track changes in the position of a touch orproximity input within touch-sensitive areas of touch sensor 101. Thestorage unit stores programming for execution by the processor unit,including programming for controlling the drive unit to supply drivesignals to the drive electrodes, programming for processing measurementsignals from the sense unit, and other suitable programming. Althoughthis disclosure describes a particular touch sensor controller having aparticular implementation with particular components, this disclosurecontemplates any suitable touch sensor controller having any suitableimplementation with any suitable components.

Tracks 104 of conductive material disposed on the substrate of touchsensor 101 couple the drive or sense electrodes of touch sensor 101 toconnection pads 106, also disposed on the substrate of touch sensor 101.As described below, connection pads 106 facilitate coupling of tracks104 to touch sensor controller 102. Tracks 104 may extend into or around(e.g., at the edges of) touch-sensitive areas of touch sensor 101. Incertain embodiments, particular tracks 104 provide drive connections forcoupling touch sensor controller 102 to drive electrodes of touch sensor101, through which the drive unit of touch sensor controller 102supplies drive signals to the drive electrodes, and other tracks 104provide sense connections for coupling touch sensor controller 102 tosense electrodes of touch sensor 101, through which the sense unit oftouch sensor controller 102 senses charge at the capacitive nodes oftouch sensor 101.

Tracks 104 are made of fine lines of metal or other conductive material.For example, the conductive material of tracks 104 may be copper orcopper-based. As another example, the conductive material of tracks 104may be silver or silver-based. In certain embodiments, tracks 104 aremade of ITO in whole or in part in addition or as an alternative to thefine lines of metal or other conductive material. Although thisdisclosure describes particular tracks made of particular materials withparticular widths, this disclosure contemplates any suitable tracks madeof any suitable materials with any suitable widths. In addition totracks 104, touch sensor 101 may include one or more ground linesterminating at a ground connector (which may be a connection pad 106) atan edge of the substrate of touch sensor 101 (similar to tracks 104).

Connection pads 106 may be located along one or more edges of thesubstrate, outside touch-sensitive areas of touch sensor 101. Asdescribed above, touch sensor controller 102 may be on an FPC.Connection pads 106 may be made of the same material as tracks 104 andmay be bonded to the FPC using an anisotropic conductive film (ACF). Incertain embodiments, connection 108 include conductive lines on the FPCcoupling touch sensor controller 102 to connection pads 106, in turncoupling touch sensor controller 102 to tracks 104 and to the drive orsense electrodes of touch sensor 101. In another embodiment, connectionpads 106 are connected to an electro-mechanical connector (such as azero insertion force wire-to-board connector); in this embodiment,connection 108 may not include an FPC, if desired. This disclosurecontemplates any suitable connection 108 between touch sensor controller102 and touch sensor 101.

FIG. 2 illustrates an example two-layer capacitive touch sensor system200 according to certain embodiments of the present disclosure. Inparticular embodiments, touch sensor system 200 may be incorporated in atouch-sensitive display application wherein touch sensor system 200 isoverlaid on a display or electrically integrated with the display. Forinstance, touch sensor system 200 may be attached to or provided as partof a desktop computer, laptop computer, tablet computer, personaldigital assistant (PDA), smartphone, satellite navigation device,portable media player, portable game console, kiosk computer,point-of-sale device, or other suitable device that senses touch inputsat its display. Further, in particular embodiments, touch sensor system200 may be incorporated in an integrated display and touch sensorapplication, where the display and touch sensor are electrically andmechanically coupled to one another in a stack (e.g., mechanical stack160 of FIG. 1D), and share one or more electrical connections and/orcomponents.

Touch sensor system 200 comprises touch sensor 210, which includes touchsensor layers 201-202. Touch sensor system 200 further comprisescontroller 220 coupled to each of layers 201-202. Each of layers 201-202includes an array of capacitive nodes formed by electrodes, which may becomprised of any suitable conductive material. For example, in certainembodiments, the electrodes of touch sensor layers 201-202 may becomposed of conductive mesh materials, such as metal meshes. As anotherexample, in certain embodiments, the electrodes of touch sensor layers201-202 may be composed of ITO. An example capacitive node of layers201-202 is described further below with respect to FIGS. 3A-3B and FIGS.4A-4D.

The capacitive nodes of layers 201 and 202 are formed by x-axis andy-axis electrodes, and may be similar to configurations 150 of FIGS.1B-1C in certain embodiments or may be similar to conductive mesh layers301-302 of FIGS. 3A-3B. The x-axis electrodes and y-axis electrodes oftouch sensor layer 201 are directly coupled to controller 220, while thex-axis electrodes and y-axis electrodes of touch sensor layer 202 arecoupled to controller 210 through buffer 230 and switch 240. Buffer 230includes circuitry for buffering signals sent by controller 220, such asa non-inverting amplifier that attenuates or amplifies the signals sentby controller 220. Although illustrated as separate components, one ormore components of buffer 230 may be incorporated into controller 220 insome embodiments. Switch 240 includes circuitry for switching between(for sending to the electrodes of layer 202) the same signals as sent tothe electrodes of layer 201 from controller 220, and driven shieldsignals from controller 220, as described further below.

In operation, touch sensor system 200 may be operated in a mutual- orself-capacitive sensing mode. During mutual-capacitive modes ofoperation, as described above, a drive signal may be sent on one or morex-axis electrodes with changes in capacitance caused by touch inputsbeing detected on one or more y-axis sensing electrodes capacitivelycoupled to the driven x-axis electrodes. More than one x-axis electrodemay be driven simultaneously. For example, a, and particular embodimentmay drive one, two, four, eight, sixteen, or any other number of x-axiselectrodes simultaneously. In system 200, during mutual-capacitive modesof touch sensing, the signals sent to or the electrodes of layer 201 bycontroller 220 may be the same as those sent to the electrodes of layer202. That is, in certain embodiments, the drive signals sent to x-axiselectrodes of layer 201 are the same as the drive signals sent to x-axisof layer 202. Sensing may be performed by detecting signals from sensingelectrodes of one or both of layers 201-202 by controller 220 accordingto mutual-capacitive sensing techniques. For instance, in certainembodiments, sensing may be performed by detecting signals on y-axiselectrodes of layer 201, layer 202, or a combination of both.

For example, the location of a touch input on touch sensor 210 may bedetermined by applying (using controller 220) a pulsed or alternatingvoltage (i.e., a drive signal) to the x-axis electrodes (i.e., driveelectrodes) of both layers 201-202, which induces a charge on y-axiselectrodes (i.e., sense electrodes) of layers 201-202 via overlapregions between the x-axis and y-axis electrodes. The induced charge(i.e., sensed signal) on the y-axis electrodes of layer 201, 202, orboth is then measured by controller 220 to determine the location of thetouch input on touch sensor 210. Because the x-axis electrodes of bothlayer 201 and layer 202 may be driven using the same signal duringmutual-capacitive modes of operation (i.e., the “X” drive signalsillustrated are sent to both layers 201-202), switch 240 may becontrolled by controller 220 to pass the same “X” drive signals to thex-axis electrodes of layer 202 as are sent to the x-axis electrodes oflayer 201 (versus sending a driven shield signal “S” to the electrodesof layer 202). The “Y” signals in FIG. 2 may refer to the sensedsignals.

During self-capacitive modes of operation on the other hand, a pulsed oralternating voltage is applied (using controller 220) to both x-axiselectrodes and y-axis electrodes of layer 201 while the x-axis andy-axis electrodes of layer 202 are driven with a driven shield signal.The location of a touch input on touch sensor 210 may thus be determinedby measuring the changes in capacitance in the capacitive nodes of layer201. The driven shield signal may be a substantially similar oridentical waveform to the drive signal applied to the x-axis and y-axiselectrodes of layer 201. In particular, the driven shield signal may bea waveform signal wherein the high reference and low reference voltages(e.g., the high and low voltages of a pulsed or alternating signal)applied to each of the measured and non-measured electrodes aresubstantially similar, reducing the changes in mutual capacitancepresent between measured and non-measured electrodes of layer 201.

In certain embodiments, not all x-axis electrodes and y-axis electrodesof layer 201 may be driven at the same time during self-capacitive modesof operation (e.g., due to limited controller resources or to conservecontroller resources). Accordingly, during such modes, a scan of theelectrodes may be performed. This may occur in three cycles (i.e., onlyone third of the sensor lines are being measured at a time), forexample, where y-axis electrodes are measured first, odd x-axiselectrodes are measured second, and even x-axis electrodes are measuredthird. In scanning embodiments, if non-measured electrodes are leftfloating (i.e., with no applied drive signal or voltage), interactionsmay take place between measured and non-measured electrodes due to themutual capacitance present between the respective electrodes.Accordingly, the driven shield signals may cancel one or more effectscaused by the mutual capacitance present between measured andnon-measured electrodes of touch sensor 210 during self-capacitive modesof operation.

During such self-capacitive modes of operation where limited numbers ofsensor lines are measured at a time, portions of the x-axis electrodesand/or y-axis electrodes of layer 201 may be driven with a drive signal(e.g., a pulsed or alternating voltage), with other portions of thex-axis electrodes and/or y-axis electrodes of layer 201 being drivenwith a driven shield signal. For example, in one embodiment, even x-axiselectrodes of layer 201 are driven for touch sensing but not the oddx-axis electrodes of layer 201. During this time, the odd x-axiselectrodes of layer 201 are driven with a driven shield signal ratherthan left to float without an applied voltage. The driven shield signalmay be a signal that is the same or substantially similar to the drivesignal applied to the even x-axis electrodes of layer 201, such that thehigh reference and low reference voltages applied to each of the evenand odd x-axis electrodes of layer 201 are substantially similar, whichreduces the changes in mutual capacitance present between measured andnon-measured electrodes of layer 201. The x-axis and y-axis electrodesof layer 202 may also be driven with a driven shield signal as well. Incertain embodiments, the signal applied to the x-axis and y-axiselectrodes of layer 202 is the same driven shield signal that is appliedto the odd x-axis electrodes of layer 201. Accordingly, switch 240 maybe controlled by controller 220 to pass the “S_(x)” and “S_(y)” drivenshield signals to the electrodes of layer 202.

Modifications, additions, or omissions may be made to touch sensorsystem 200 without departing from the scope of the invention. Forexample, although particular electrodes are referred to above as sendingdrive signals to x-axis electrodes and sensing y-axis electrodes inmutual-capacitive modes of operation, it will be understood that thedrive signals may be sent to y-axis electrodes with sensing performedusing x-axis electrodes. As another example, although described withregard to three cycles, touch sensor scanning may be performed in anysuitable number of cycles.

FIGS. 3A-3B illustrate an example capacitive node 300 of a two-layertouch sensor according to certain embodiments of the present disclosure.As described above, layers 301-302 may each comprise an array ofcapacitive nodes formed by electrodes, and may be used in a touch sensorsimilar to touch sensor 210 of FIG. 2, with layers 301-302 correspondingto layers 201-202 of FIG. 2, respectively. Capacitive node 300represents a single sensing area or coordinate of a touch sensor in thisexample. FIGS. 3A-3B illustrate bird's eye views of layers 301-302 incapacitive node 300. Capacitive node 300 of FIGS. 3A-3B is formed bylayers 301-302, which are each a mesh of conductive material in thisexample. In other embodiments, capacitive node 300 may be formed by twolayers of any suitable array of capacitive nodes, such as two layers ofcapacitive nodes formed by overlapping ITO electrodes or two layers ofcapacitive nodes formed by differing types of conductive materials(e.g., layer 301 formed of conductive mesh and layer 302 formed ofoverlapping ITO electrodes). Although illustrated in a side-by-sideconfiguration, it will be understood that layer 301 is disposed abovelayer 302 in a mechanical stack, such that the crossover region 305 ofeach layer is substantially aligned. In this embodiment, layer 301represents a top layer of a two-layer touch sensor, similar to layer 201of touch sensor system 200 of FIG. 2. Likewise, layer 302 represents abottom layer of a two-layer touch sensor, similar to layer 202 of touchsensor system 200 of FIG. 2.

Layer 301 comprises a first portion 310, a second portion 320, and athird portion 330. Each of first portion 310, second portion 320, andthird portion 330 are electrically uncoupled from one another. This maybe done by forming the mesh without such coupling connections, or byde-coupling existing connections in the mesh. First portion 310 andsecond portion 320 may overlap with one another (via second portion 320being coupled to a portion of layer 302 as described below) to formcrossover region 305. Third portion 330 is within the crossover region305 of first portion 310 and second portion 320, but is electricallycoupled to a portion of layer 302 as described below. Similar to layer301, layer 302 comprises a first portion 330, a second portion 340, anda third portion 320. First portion 330 of layer 302 corresponds withfirst portion 310 of layer 301, and vice versa. Likewise, second portion340 of layer 302 corresponds with second portion 320 of layer 301, andvice versa. Each of first portion 330, second portion 340, and thirdportion 320 are electrically uncoupled from one another. This may bedone by forming the mesh without such coupling connections, or byde-coupling existing connections in the mesh. First portion 330 andsecond portion 340 may overlap with one another (via first portion 330being coupled to a portion of layer 301 as described below) to formcrossover region 305. Third portion 320 is within the crossover region305 of first portion 330 and second portion 340, but is electricallycoupled to a portion of layer 301 as described below.

Modifications, additions, or omissions may be made to capacitive node300 without departing from the scope of the invention. For example,although illustrated in FIGS. 3A-3B and described above as being layersof conductive mesh comprising arrays of capacitive nodes, layers 301-302may be include any suitable array of capacitive nodes. For example, eachof layers 301-302 may comprise arrays of capacitive nodes formed byoverlapping ITO electrodes or other suitable types of conductivematerials.

FIGS. 4A-4D illustrate blow-up and cross-sectional views of crossoverregion 305 of capacitive node 300 of FIGS. 3A-3B in accordance withcertain embodiments of the present disclosure. More particularly, FIG.4A illustrates a cross-section view of conductive mesh layer 301 atcutaway 361, FIG. 4B illustrates a cross-section view of conductive meshlayer 301 at cutaway 362, FIG. 4C illustrates a cross-section view ofconductive mesh layer 302 at cutaway 363, and FIG. 4D illustrates across-section view of conductive mesh layer 302 at cutaway 364. Asillustrated in FIGS. 4A-4B, crossover region 305 comprises a firstportion 310, a second portion 320, and a third portion 330 of theconductive mesh 301. Each respective portion of the conductive mesh 301in crossover region 305 is electrically uncoupled from the otherrespective portions of the conductive mesh 301 in the crossover region305. Similarly, as illustrated in FIGS. 4C-4D, crossover region 305comprises a first portion 330, a second portion 340, and a third portion320 of the conductive mesh 302, wherein each respective portion of thesecond conductive mesh in the crossover region 305 is electricallyuncoupled from the other respective portions of the second conductivemesh in the crossover region 305. The third portion 330 of theconductive mesh 301 is coupled to the first portion 330 of theconductive mesh 302, and the third portion 320 of the conductive mesh302 is coupled to the second portion 320 of the conductive mesh 302.These couplings are made using one or more vias 350 disposed betweenconductive meshes 301 and 302. As shown, in some embodiments eachcoupling of mesh portions may require six electrical couplings.

The first portion 310 and the second portion 330 of conductive mesh 301are substantially triangular (forming a diamond pattern in the array oflayer 301), similar to first portion 330 and second portion 340 ofconductive mesh 302. However, it will be understood any suitable shapemay be used for the various portions of conductive meshes forming theelectrodes of the respective layers in accordance with embodiments ofthe present disclosure, such as rectangular (or straight) shapes.Furthermore, the first conductive mesh and the second conductive meshmay be metal meshes, in some embodiments, and may be composed of amaterial such as copper, silver, carbon, a copper-based material, asilver-based material, or a carbon-based material.

FIG. 5 illustrates an example method 500 of controlling a two-layertouch sensor in accordance with embodiments of the present disclosure.Method 500 may be performed by logic (e.g., hardware or software) of atouch sensor controller. For example, method 500 may be performed byexecuting (with one or more processors of the touch sensor controller)instructions stored in a computer-readable medium of the touch sensorcontroller. The method begins at step 510, where it is determinedwhether the touch sensor is to be operated in a mutual- orself-capacitive mode.

If the touch sensor is to be operated in a mutual-capacitive mode, thenthe method continues to steps 520 and 530, where the x-axis electrodesof the top and bottom layers of the touch sensor are driven and touchinputs are sensed using the y-axis electrodes of one or both layers,respectively. This may include, for example, sending a first drivesignal to one or more x-axis electrodes of a first array of capacitivenodes, sending the first drive signal to one or more x-axis electrodesof a second array of capacitive nodes disposed below the first array ofcapacitive nodes, and sensing touch inputs based on signals receivedfrom y-axis electrodes of the first array. In some embodiments, sendingthe second drive signal to the first plurality of the electrodes of thefirst array comprises sending the second drive signal to a first portionof the electrodes of the first array and sending the shield signal to asecond portion of the electrodes of the first array. The first drivesignal may be a pulsed or alternating signal, in certain embodiments.

If the touch sensor is to be operated in a self-capacitive mode, thenthe method continues to steps 540 and 550, where one or more x-axiselectrodes and one or more y-axis electrodes of the top layer are drivenand the electrodes of the bottom layer are driven with a shield signal,respectively. This may include, for example, sending a second drivesignal to a first plurality of the electrodes of the first array,sending a shield signal to each of the electrodes of the second array,and sensing touch inputs based on signals received from the firstplurality of electrodes of the first array. The first drive signal andthe second drive signal may be pulsed or alternating signals, in certainembodiments, and the shield signal is substantially similar to thesecond drive signal.

According to at least one embodiment of the present disclosure, a touchsensor includes a first array of capacitive nodes and a second array ofcapacitive nodes. The capacitive nodes of the first array are disposedabove the capacitive nodes of the second array forming a plurality ofcrossover regions. Each crossover region includes a first portion, asecond portion, and a third portion of the first array, wherein eachrespective portion of the first array in the crossover region iselectrically uncoupled from the other respective portions of the firstconductive mesh in the crossover region. Each crossover region furtherincludes a first portion, a second portion, and a third portion of thesecond array, wherein each respective portion of the second array in thecrossover region is electrically uncoupled from the other respectiveportions of the second conductive mesh in the crossover region. Thethird portion of the first array is coupled to the first portion of thesecond array, and the third portion of the second array is coupled tothe second portion of the first array.

In one or more of the embodiments described above, the first arraycomprises a first conductive mesh, and the second array comprises asecond conductive mesh.

In one or more of the embodiments described above, the third portion ofthe first conductive mesh is coupled to the first portion of the secondconductive mesh using a first set of vias disposed between the firstconductive mesh and the second conductive mesh, and the third portion ofthe second conductive mesh is coupled to the first portion of the firstconductive mesh using a second set of vias disposed between the firstconductive mesh and the second conductive mesh. In one or more of theembodiments described above, the first set of vias and the second set ofvias are composed of the same material as the first conductive mesh andthe second conductive mesh. In one or more of the embodiments describedabove, the first conductive mesh and the second conductive mesh aremetal meshes.

In one or more of the embodiments described above, the first arraycomprises ITO electrodes, and the second array comprises ITO electrodes.

In one or more of the embodiments described above, each crossover regionforms at least one capacitive node of the touch sensor.

In one or more of the embodiments described above, the first portion andthe second portion of the first array are substantially triangular. Inone or more of the embodiments described above, the first portion andthe second portion of the first array are rectangular.

In one or more of the embodiments described above, a controller iscoupled to the touch sensor. The controller comprises instructionsembodied in a computer-readable medium, and the instructions areconfigured, when executed by a processor of the controller, to operatein either a mutual-capacitive mode or a self-capacitive mode ofoperation. When in the mutual-capacitive mode of operation, theinstructions are operable, when executed, to send a first drive signalto x-axis electrodes of the first array, and send the first drive signalto x-axis electrodes of the second array. When in the self-capacitivemode of operation, the instructions are operable, when executed, to senda second drive signal to x-axis electrodes of the first array, send thesecond drive signal to y-axis electrodes of the first array, and send ashield signal to electrodes of the second array.

According to at least one embodiment of the present disclosure, a touchsensor includes a first conductive mesh and a second conductive meshforming a plurality of crossover regions. Each crossover region forms acapacitive node of the touch sensor. Each crossover region includes afirst portion, a second portion, and a third portion of the firstconductive mesh, wherein each respective portion of the first conductivemesh in the crossover region is electrically uncoupled from the otherrespective portions of the first conductive mesh in the crossoverregion. Each crossover region further includes a first portion, a secondportion, and a third portion of the second conductive mesh, wherein eachrespective portion of the second conductive mesh in the crossover regionis electrically uncoupled from the other respective portions of thesecond conductive mesh in the crossover region. The third portion of thefirst conductive mesh is coupled to the first portion of the secondconductive mesh using a first set of vias disposed between the firstconductive mesh and the second conductive mesh. The third portion of thesecond conductive mesh is coupled to the second portion of the firstconductive mesh using a second set of vias disposed between the firstconductive mesh and the second conductive mesh. The first portion andthe second portion of the first conductive mesh are substantiallytriangular, and the first portion and the second portion of the secondconductive mesh are substantially triangular.

In one or more of the embodiments described above, the touch sensor iscoupled to a display and a touch sensor controller. In one or moreembodiments of the embodiments described above, the touch sensor is aportion of a touch-sensitive device.

Herein, a computer-readable non-transitory storage medium or media mayinclude one or more semiconductor-based or other integrated circuits(ICs) (such, as for example, field-programmable gate arrays (FPGAs) orapplication-specific ICs (ASICs)), hard disk drives (HDDs), hybrid harddrives (HHDs), optical discs, optical disc drives (ODDs),magneto-optical discs, magneto-optical drives, floppy diskettes, floppydisk drives (FDDs), magnetic tapes, solid-state drives (SSDs),RAM-drives, SECURE DIGITAL cards or drives, any other suitablecomputer-readable non-transitory storage media, or any suitablecombination of two or more of these. A computer-readable non-transitorystorage medium may be volatile, non-volatile, or a combination ofvolatile and non-volatile.

Herein, “or” is inclusive and not exclusive, unless expressly indicatedotherwise or indicated otherwise by context. Therefore, herein, “A or B”means “A, B, or both,” unless expressly indicated otherwise or indicatedotherwise by context. Moreover, “and” is both joint and several, unlessexpressly indicated otherwise or indicated otherwise by context.Therefore, herein, “A and B” means “A and B, jointly or severally,”unless expressly indicated otherwise or indicated otherwise by context.

This disclosure encompasses a myriad of changes, substitutions,variations, alterations, and modifications to the example embodimentsherein that a person having ordinary skill in the art would comprehend.Similarly, the appended claims encompass all changes, substitutions,variations, alterations, and modifications to the example embodimentsherein that a person having ordinary skill in the art would comprehend.Moreover, reference in the appended claims to an apparatus or system ora component of an apparatus or system being adapted to, arranged to,capable of, configured to, enabled to, operable to, or operative toperform a particular function encompasses that apparatus, system,component, whether or not it or that particular function is activated,turned on, or unlocked, as long as that apparatus, system, or componentis so adapted, arranged, capable, configured, enabled, operable, oroperative.

What is claimed is:
 1. A device, comprising: a touch sensor comprising:a first array comprising a first plurality of electrodes; a second arraycomprising a second plurality of electrodes; wherein the first pluralityof electrodes of the first array are substantially aligned with thesecond plurality of electrodes of the second array in a mechanicalstack; and a controller coupled to the touch sensor, the controllercomprising logic configured, when executed, to cause the controller to:send a first signal to at least a portion of the first plurality ofelectrodes of the first array; send a second signal to at least aportion of the second plurality of electrodes of the second array; andsense touch inputs based on signals received from one or more of thefollowing: one or more electrodes of the first plurality of electrodesof the first array; and one or more electrodes of the second pluralityof electrodes of the second array; wherein the alignment of the firstplurality of electrodes of the first array and the second plurality ofelectrodes of the second array forms a plurality of crossover regions,each crossover region comprising a first portion, a second portion, anda third portion of the first array, each respective portion of the firstarray in the crossover region electrically uncoupled from the otherrespective portion of the first array in the crossover region.
 2. Thedevice of claim 1, wherein the controller is configured to operate in amutual-capacitive sensing mode.
 3. The device of claim 1, wherein: eachcrossover region further comprises a first portion, a second portion,and a third portion of the second array; and each respective portion ofthe second array in the crossover region is electrically uncoupled fromthe other respective portions of the second array in the crossoverregion.
 4. The device of claim 1, wherein the first signal is a drivesignal and the second signal is the same drive signal as the firstsignal.
 5. The device of claim 1, wherein the third portion of the firstarray is coupled to a portion of the second array.
 6. The device ofclaim 1, wherein the electrodes of the first array and the electrodes ofthe second array are composed of a conductive mesh.
 7. The device ofclaim 1, wherein the electrodes of the first array and the electrodes ofthe second array are composed of indium tin oxide (ITO).
 8. A touchsensor controller comprising logic configured, when executed by thetouch sensor controller, to: send a first signal to at least a portionof a first plurality of electrodes of a first array of a touch sensor;send a second signal to at least a portion of a second plurality ofelectrodes of a second array of the touch sensor; and sense touch inputsbased on signals received from one or more of the following: one or moreelectrodes of the first plurality of electrodes of the first array; andone or more electrodes of the second plurality of electrodes of thesecond array; wherein: the first plurality of electrodes of the firstarray are substantially aligned with the second plurality of electrodesof the second array in a mechanical stack; and the alignment of thefirst plurality of electrodes of the first array and the secondplurality of electrodes of the second array forms a plurality ofcrossover regions, each crossover region comprising a first portion, asecond portion, and a third portion of the first array, each respectiveportion of the first array in the crossover region electricallyuncoupled from the other respective portion of the first array in thecrossover region.
 9. The touch sensor controller of claim 8, wherein thetouch sensor controller is configured to operate in a mutual-capacitivesensing mode.
 10. The touch sensor controller of claim 8, wherein: eachcrossover region further comprising a first portion, a second portion,and a third portion of the second array; and each respective portion ofthe second array in the crossover region is electrically uncoupled fromthe other respective portions of the second array in the crossoverregion.
 11. The touch sensor controller of claim 8, wherein the firstsignal is a drive signal and the second signal is the same drive signalas the first signal.
 12. The touch sensor controller of claim 8, whereinthe third portion of the first array is coupled to a portion of thesecond array.
 13. The touch sensor controller of claim 8, wherein theelectrodes of the first array and the electrodes of the second array arecomposed of a conductive mesh.
 14. The touch sensor controller of claim8, wherein the electrodes of the first array and the electrodes of thesecond array are composed of indium tin oxide (ITO).
 15. A method,comprising: sending a first signal to at least a portion of a firstplurality of electrodes of a first array of a touch sensor; sending asecond signal to at least a portion of a second plurality of electrodesof a second array of the touch sensor; and sensing touch inputs based onsignals received from one or more of the following: one or moreelectrodes of the first plurality of electrodes of the first array; andone or more electrodes of the second plurality of electrodes of thesecond array; wherein: the first plurality of electrodes of the firstarray are substantially aligned with the second plurality of electrodesof the second array in a mechanical stack; and the alignment of thefirst plurality of electrodes of the first array and the secondplurality of electrodes of the second array forms a plurality ofcrossover regions, each crossover region comprising a first portion, asecond portion, and a third portion of the first array, each respectiveportion of the first array in the crossover region electricallyuncoupled from the other respective portion of the first array in thecrossover region.
 16. The method of claim 15, wherein: each crossoverregion further comprising a first portion, a second portion, and a thirdportion of the second array; and each respective portion of the secondarray in the crossover region is electrically uncoupled from the otherrespective portions of the second array in the crossover region.
 17. Themethod of claim 15, wherein the first signal is a drive signal and thesecond signal is the same drive signal as the first signal.
 18. Thetouch sensor controller of claim 15, wherein the third portion of thefirst array is coupled to a portion of the second array.
 19. The methodof claim 15, wherein the electrodes of the first array and theelectrodes of the second array are composed of a conductive mesh. 20.The method of claim 15, wherein the electrodes of the first array andthe electrodes of the second array are composed of indium tin oxide(ITO).